Lumbar puncture
A lumbar puncture (or LP, and colloquially known as a spinal tap) is a diagnostic and at times therapeutic procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis, or very rarely as a treatment ("therapeutic lumbar puncture") to relieve increased intracranial pressure. It is one of the most common diagnostic procedures performed on House, M.D. History The first technique for accessing the dural space was described by the London physician Dr. Walter Essex Wynter. In 1889, he developed a crude procedure to insert fluid drainage tubes in 4 patients with tuberculous meningitis. The main purpose was the treatment of raised intracranial pressure rather than for diagnosis. The technique for needle lumbar puncture was then introduced by the German physician Heinrich Quincke, who credits Wynter with the earlier discovery. Quincke first reported his experiences at an internal medicine conference in Wiesbaden in 1891. He subsequently published a book on the subject. The lumbar puncture procedure was taken to the United States by Arthur H. Wentworth M.D., an assistant professor at the Harvard Medical School, based at Children's Hospital. In 1893, he published a long paper on diagnosing cerebrospinal meningitis by examining spinal fluid. His career took a nosedive, however, when antivivisectionists prosecuted him for having obtained spinal fluid from children. He was acquitted, but he was uninvited from the then forming Johns Hopkins School of Medicine, where he would have been the first professor of pediatrics. Indications The most common purpose for a lumbar puncture is to collect cerebrospinal fluid in a case of suspected meningitis, since there is no other reliable tool with which meningitis, a life-threatening but highly treatable condition, can be excluded. Young infants commonly require lumbar puncture as a part of the routine workup for fever without a source, as they have a much higher risk of meningitis than older persons and do not reliably show signs of meningeal irritation. In any age group, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension and many other diagnoses may be supported or excluded with this test. Lumbar punctures may also be done to inject medications into the cerebrospinal fluid ("intrathecally"), particularly for spinal anesthesia or chemotherapy. It may also be used to detect the presence of malignant cells in the CSF, as in carcinomatous meningitis or medulloblastoma. Contraindications Lumbar puncture should not be performed in the following situations * Idiopathic increased intracranial pressure (ICP) ** Rationale: lumbar puncture in the presence of increased ICP may cause uncal herniation ** Exception: therapeutic use of lumbar puncture to reduce ICP ** Precaution *** CT Scan of the brain is advocated by some, especially in the following situations **** Age over 65 **** Reduced Glasgow Coma Scale or conscious state **** Recent history of seizure **** Focal neurological signs *** Ophthalmoscopy for papilledema * Hereditary bleeding conditions ** Coagulopathy ** Decreased platelet count * Certain Infections ** Skin infection at puncture site ** Sepsis * Abnormal respiratory pattern * High blood pressure with bradycardia and deteriorating consciousness * Vertebral deformities (scoliosis or kyphosis), in hands of an inexperienced physician. Procedure In performing a lumbar puncture, first the patient is usually placed in a left (or right) lateral position with the neck bent in full flexion and knees bent in full flexion up to the chest, approximating a fetal position as much as possible. It is also possible to have the patient sit on a stool and bend their head and shoulders forward. The area around the lower back is prepared using aseptic technique. Once the appropriate location is palpated, local anasthetic is infiltrated under the skin and then injected along the intended path of the spinal needle. A spinal needle is inserted between the lumbar vertebrae L3/L4 or L4/L5 and pushed in until there is a "give" that indicates the needle is past the ligamentum flavum. The needle is again pushed until there is a second 'give' that indicates the needle is now past the dura mater. Since the arachnoid membrane and the dura mater exist in flush contact with one another in the living person's spine (due to fluid pressure from CSF in the subarachnoid space pushing the arachnoid membrane out towards the dura), once the needle has pierced the dura mater it has also traversed the thinner arachnoid membrane and is now in the subarachnoid space. The stylet from the spinal needle is then withdrawn and drops of cerebrospinal fluid are collected. The opening pressure of the cerebrospinal fluid may be taken during this collection by using a simple column manometer. The procedure is ended by withdrawing the needle while placing pressure on the puncture site. In the past, the patient would often be asked to lie on their back for at least six hours and be monitored for signs of neurological problems, though there is no scientific evidence that this provides any benefit. The technique described is almost identical to that used in spinal anesthesia, except that spinal anesthesia is more often done with the patient in a seated position. The upright seated position is advantageous in that there is less distortion of spinal anatomy which allows for easier withdrawal of fluid. It is preferred by some practitioners when a lumbar puncture is performed on an obese patient where having them lie on their side would cause a scoliosis and unreliable anatomical landmarks. On the other hand, opening pressures are notoriously unreliable when measured on a seated patient and therefore the left or right lateral (lying down) position is preferred if an opening pressure needs to be measured. Patient anxiety during the procedure can lead to increased CSF pressure, especially if the person holds their breath, tenses their muscles or flexes their knees too tightly against their chest. Diagnostic analysis of changes in fluid pressure during lumbar puncture procedures requires attention both to the patient's condition during the procedure and to their medical history. Reinsertion of the stylet may decrease the rate of post lumbar puncture headaches. Risks Post spinal headache with nausea is the most common complication; it often responds to analgesics and infusion of fluids. It was long taught that this complication can often be prevented by strict maintenance of a supine posture for two hours after the successful puncture. However, this has not been borne out in modern studies involving large numbers of patients. Merritt's Neurology (10th edition), in the section on lumbar puncture, notes that intravenous caffeine injection is often quite effective in aborting these so-called spinal headaches. Contact between the side of the lumbar puncture needle and a spinal nerve root can result in anomalous sensations (paresthesia) in a leg during the procedure. This is harmless and patients can be warned about it in advance to minimize their anxiety if it should occur. A headache that is persistent despite a long period of bedrest and occurs only when sitting up may be indicative of a CSF leak from the lumbar puncture site. It can be treated by more bedrest, or by an epidural blood patch, where the patient's own blood is injected back into the site of leakage to cause a clot to form and seal off the leak. Serious complications of a properly performed lumbar puncture are extremely rare. They include spinal or epidural bleeding, adhesive arachnoiditis and trauma to the spinal cord or spinal nerve roots resulting in weakness or loss of sensation, or even paraplegia. The latter is exceedingly rare, since the level at which the spinal cord ends (normally the inferior border of L1, although it is slightly lower in infants) is several vertebral spaces above the proper location for a lumbar puncture (L3/L4). There are case reports of lumbar puncture resulting in perforation of abnormal dural arterio-venous malformations, resulting in catastrophic epidural hemorrhage. This is exceedingly rare. The procedure is not recommended when epidural infection is present or suspected, when topical infections or dermatological conditions pose a risk of infection at the puncture site (e.g. third-degree burns) or in patients with severe psychosis or neurosis with back pain. Some authorities believe that withdrawal of fluid when initial pressures are abnormal could result in spinal cord compression or cerebral herniation; others believe that such events are merely coincidental in time, occurring independently as a result of the same pathology that the lumbar puncture was performed to diagnose. In any case, computed tomography of the brain is often performed prior to lumbar puncture if an intracranial mass is suspected. Removal of cerebrospinal fluid resulting in reduced fluid pressure has been shown to correlate with greater reduction of cerebral blood flow among patients with Alzheimer's disease. Its clinical significance is uncertain. Diagnostics Increased CSF pressure can indicate congestive heart failure, cerebral edema, subarachnoid hemorrhage, hypo-osmolality resulting from hemodialysis, meningeal inflammation, purulent meningitis or tuberculous meningitis, hydrocephalus, or pseudotumor cerebri. Decreased CSF pressure can indicate complete subarachnoid blockage, leakage of spinal fluid, severe dehydration, hyperosmolality, or circulatory collapse. Significant changes in pressure during the procedure can indicate tumors or spinal blockage resulting in a large pool of CSF, or hydrocephalus associated with large volumes of CSF. Lumbar puncture for the purpose of reducing pressure is performed in some patients with idiopathic intracranial hypertension (also called pseudotumor cerebri.) The presence of white blood cells in cerebrospinal fluid is called pleocytosis. A small number of monocytes can be normal; the presence of granulocytes is always an abnormal finding. A large number of granulocytes often heralds bacterial meningitis. White cells can also indicate reaction to repeated lumbar punctures, reactions to prior injections of medicines or dyes, central nervous system hemorrhage, leukemia, recent epileptic seizure, or a metastatic tumor. When peripheral blood contaminates the withdrawn CSF, a common procedural complication, white blood cells will be present along with erythrocytes, and their ratio will be the same as that in the peripheral blood. The finding of erythrophagocytosis where phagocytosed erythrocytes is observed, signifies bleeding into the CSF that preceded the lumbar puncture. Therefore, when erythrocytes are detected in the CSF sample, erythrophagocytosis suggests causes other than a traumatic tap, such as intracranial haemorrhage and haemorrhagic herpetic encephalitis. In which case, further investigations are warranted, including imaging and viral culture. Several substances found in cerebrospinal fluid are available for diagnostic measurement. * Measurement of chloride levels may aid in detecting the presence of tuberculous meningitis. * Glucose is usually present in the CSF; the level is usually about 60% that in the peripheral circulation. A fingerstick or venipuncture at the time of lumbar puncture may therefore be performed to assess peripheral glucose levels in order to determine a predicted CSF glucose value. Decreased glucose levels can indicate fungal, tuberculous or pyogenic infections; lymphomas; leukemia spreading to the meninges; meningoencephalitic mumps; or hypoglycemia. A glucose level of less than one third of blood glucose levels in association with low CSF lactate levels is typical in hereditary CSF glucose transporter deficiency also known as De Vivo disease. * Increased glucose levels in the fluid can indicate diabetes, although the 60% rule still applies. * Increased levels of glutamine are often involved with hepatic encephalopathies, Reye's syndrome, hepatic coma, cirrhosis and hypercapnia. * Increased levels of lactate can occur the presence of cancer of the CNS, multiple sclerosis, heritable mitochondrial disease, low blood pressure, low serum phosphorus, respiratory alkalosis, idiopathic seizures, traumatic brain injury, cerebral ischemia, brain abscess, hydrocephalus, hypomania or bacterial meningitis. * The enzyme lactate dehydrogenase can be measured to help distinguish meningitides of bacterial origin, which are often associated with high levels of the enzyme, from those of viral origin in which the enzyme is low or absent. * Changes in total protein content of cerebrospinal fluid can result from pathologically increased permeability of the blood-cerebrospinal fluid barrier, obstructions of CSF circulation, meningitis, neurosyphilis, brain abscesses, subarachnoid hemorrhage, polio, collagen disease or Guillain-Barre syndrome, leakage of CSF, increases in intracranial pressure or hyperthyroidism. Very high levels of protein may indicate tuberculous meningitis or spinal block. * IgG synthetic rate is calculated from measured IgG and total protein levels; it is elevated in immune disorders such as multiple sclerosis, transverse myelitis, and neuromyelitis optica of Devic. * Numerous antibody-mediated tests for CSF are available in some countries: these include rapid tests for antigens of common bacterial pathogens, treponemal titers for the diagnosis of neurosyphilis and Lyme disease, Coccidioides antibody, and others. * The India ink test is still used for detection of meningitis caused by Cryptococcus neoformans, but the cryptococcal antigen (CrAg) test has a higher sensitivity. * CSF can be sent to the microbiology lab for various types of smears and cultures to diagnose infections. * Polymerase chain reaction (PCR) has been a great advance in the diagnosis of some types of meningitis. It has high sensitivity and specificity for many infections of the CNS, is fast, and can be done with small volumes of CSF. Even though testing is expensive, it saves cost of hospitalization. Appearances Lumbar puncture is a commonly depicted procedure on House, M.D.. It has appeared in almost every episode of the series. Therapy In Paternity, Dan's symptoms intitially pointed to neurosyphillis. He needed an injection of penicillin directly into his cerebro-spinal fluid, but he already had high CSF pressure. House suggested, that they do an LP and inject the penicillin directly through the puncture point. As the patient already had a shunt in place, the excess pressure could drain through it. However, when they did the LP, the patient started hallucinating. In addition, the treatment didn't work. Outbreak The series' only true exposure to meningitis was in Kids, when a crowd at a swimming competition was exposed to an active case. About a third of the crowd was sent to Princeton-Plainsboro Teaching Hospital where the staff was overwhelmed by having to screen about 800 people for outward symptoms of the disease - fever, a stiff neck and a rash. Those who met the criteria had to be quarantined and receive further tests to confirm. While being forced to do routine examinations by Cuddy, House came across a young diver who meet all of the criteria. However, the diver insisted she had had the rash for about a week (a meningitis rash kills within a couple of days) and House noted that she only had stiffness in one direction. He convinced Cuddy the diver may not have meningitis and got Chase and Foreman assigned to him to work on the diver for one hour before they had to return to screen other patients. However, even House had to admit he may be wrong and ordered Foreman to do a lumbar puncture to rule out meningitis. Foreman went to Nurse Previn to try to get a procedure room, but she turned him down due to the work from the outbreak. As a result, Foreman and the diver's coach performed the lumbar puncture while she was lying on a gurney. After the procedure, an orderly came to get the gurney, and the diver had to be moved to a couch. Foreman admonished the orderly, who apologized and said he needed the gurney. Foreman reminded him that LP patients usually require several hours of rest without being moved post procedure in order to avoid complications. Luckily, the LP ruled out meningitis. The Workaround With Foreman in charge in Deception, House was trying to convince him that Anica Jovanovich's symptoms are the result of a recurrence of her Cushing's syndrome. However, Foreman is sure it's an infection and orders an LP. He also orders House to perform it. However, House is not about to be defeated that easily. Instead of doing the LP in a straightforward manner, he instead seems to be clumsy and pokes her repeatedly with the needle. Her blood pressure spikes, showing a hypertensive crisis typical of Cushing's. Foreman concedes and allows House to scan for a microtumor once they rule out alcohol withdrawal. The Feint In Failure to Communicate, Foreman was still technically in charge of the case of aphasic journalist Fletcher Stone, but when he ran out of ideas, he finally got in touch with House, who was in Baltimore dealing with Medicaid. House suspects the patient in still hiding something, but he's so committed to concealing it, they have to scare it out of him. He tells the team to confront the patient to see if he's hiding something and make it clear to him that he will die if he's keeping something back. He also orders Cameron to do an LP in case it is meningitis or multiple sclerosis, despite the risk of paralysis given the patient's condition. Foreman and Chase dutifully tell the patient he will most likely die if he's holding something back, but he remains silent. However, as Cameron goes to do the LP, she tries to comfort the patient. This makes the patient start blurting out "I couldn't handle the bear! They took my stain!". House later admits to Cameron that she knew he would comfort the patient and that he was setting up a "good cop, bad cop" situation to put the pressure on the patient. The patient's outburst eventually leads House to the right answer. The Dilemma Patients with burns that cover the spine cannot receive an LP - the burned skin cannot be properly sterilized and it is likely any biological pathogens on the skin would contaminate the CSF and cause a fatal infection. However, in the episode Distractions, the patient Adam suffered from such burns, and his symptoms pointed to either an infection or multiple sclerosis. With options running out, House ordered a cervical puncture, which is performed much higher on the neck and poses a far greater risk of paralysis. Despite objections from the team, House said they had no other choice and they convinced the patient's parents to consent. The procedure did not go well. Foreman tried to insert the needle in the C2:C3 space, but could find no passage. He decided to move up one vertebrae to C1:C2. Chase warned him of the possibility of a brain hernia, and, in addition, Adam's blood pressure started to spike, risking a stroke. Foreman managed to complete the procedure. However, the tests on the CSF were negative. Side Effects It doesn't happen very often, but on occasion one procedure provides a totally unrelated clue. In Whac-A-Mole, the most likely cause of Jack Walters' vomiting was an infection. As such, House ordered Foreman to do an LP. The procedure went smoothly and Foreman even got help from Jack's younger sister Kama. However, as they rolled him onto his back after the procedure, they broke one of Jack's ribs and realized he also had osteomyelitis. On The Fly While flying back from Singapore in the episode Airborne, Gregory House and Lisa Cuddy found themselves with a passenger who was suffering from nausea, rash vomiting and ataxia. Even worse, no-one on the flight spoke the passenger's language, Korean, so getting a medical history was impossible. Cuddy was sure that the passenger had bacterial meningitis and wanted to land the plane immediately. However, House thought she was panicking and played down the risk. However, when another woman and Cuddy came down with the same symptoms, the plane was past it's point of no return and had to continue on to New York. It was likely that most of the passengers would become infected by then if it was meningitis. After ruling out several other possibilities, House realized he had to jury rig a lumbar puncture using an emergency syringe. Given the likely turbulence, the procedure might result in spinal cord damage. However, House completed the procedure successfully and saw the cerebro-spinal fluid was clear. He realized the rest of the sick people were suffering from conversion disorder, but still had no answer for the original sick passenger, who continued to get sicker. Basic Skills Due to her involvement with House, Martha M. Masters didn't always get time to meet the practical requirements for graduating medical school. In Last Temptation, on the last day of classes, Masters was still trying to perform her tenth and last lumbar puncture. At first, her classmate Cruz did two lumbar punctures (giving him well over ten) in order to thwart her. However, when she learned of another patient, she found that House had beat her to the patient and performed the procedure himself. He then took Masters' log book and confirmed that she had done the LP. Masters protested, but House asked if she knew how to do an LP. Masters said of course she did, and House countered if she knew how to do nine LPs and say she did ten. He told Masters he would hire her as an intern if she turned in her log book. However, Masters couldn't do it. Instead, when Thirteen found out about it, she let Masters do a routine LP on her to meet the requirement. When Masters turned in her completed log book, House took one look at Thirteen and realized she had had a recent LP. He fired Masters on the spot. Other appearances *Jeff Forrester is given an LP in Spin to rule out infection. *George narrowly avoided an LP in Que Sera Sera when he regained consciousness just after Cameron suggested the procedure. *During House's hallucination in No Reason, he decides to do a high risk LP on Vince because he has run out of other options. Like all the other "tests", it is negative. *Boyd and his father Walter refuse an LP, as well as any other procedure, after the diagnosis of Boyd's tuberous sclerosis in House vs. God *In Acceptance, Foreman uses the procedure to deliberately cause a little more pain for Clarence, a death-row inmate. When Clarence complains, Foreman asks why a tough guy like him can't take it. *In Merry Little Christmas, Cuddy is struggling for a diagnosis for Abigail Ralphean and orders an LP along with other tests. However, her uncertainty merely convinces the patient's mother that the doctors have no idea what's wrong with her. In other languages This article was largely developed from the article of the same name at Wikipedia http://en.wikipedia.org/wiki/Lumbar_puncture Category:Medical procedures